Articulations in vehicle seats are currently used either for adjusting inclination of the backing portion of a seat or for adjusting inclination of the seating portion of the seat, the latter also being called an adjustment of the seat trim. Some articulations are generally designated as a micrometric type, enabling an extremely fine adjustment of the positions, that is practically an adjustment hardly perceptible when a small rotation is imparted via a control knob.
In such micrometric articulations, it is necessary that a planet wheel including two adjacent toothings is interposed between the fixed and mobile toothings of the flanges.
Conventionally, the larger diameter toothing of the planet wheel is made by a cutting step after a die stamping step of the smaller diameter toothing.
It will be therefore easily understood that the larger diameter toothing thus made is connected to the mass of the planet wheel only by means of the basis of the toothing, and that only the smaller diameter toothing is adjacent the face of the larger diameter toothing.
Due to this fact, the force necessary for flexing the teeth and breaking them has a value which is rather quickly reached. If the planet wheel is deteriorated, the articulation has then to be totally replaced.